1. Field of the Invention
A playback device including a spindle motor rotating a disc-type recording medium, an optical pickup performing playback of information of the disc-type recording medium and a thread motor moving the optical pickup in a radial direction of the disc-type recording medium is known.
2. Description of Related Art
As shown in FIG. 34 and FIG. 35, a thread motor 301 is attached to a stator substrate 302 as a motor supporting plate in a pendent state under a chassis 303 by means of a screw 304, an adhesive and the like so that an outer peripheral portion of the stator substrate 302 is overlapped with an undersurface of the chassis 303. A first gear 307 included in a transmission gear group 306 transmitting the rotation of a rotor 305 to the optical pickup is provided at an undersurface of the rotor 305 of the thread motor 301. The transmission gear group 306 includes a first gear 307, a second gear 308 engaged with the first gear 307, a first worm gear 309 integrally formed with the second gear 308 and a second worm gear 310 engaged with the first worm gear 309. The second worm gear 310 is fixed to a lead screw 311, and the rotation of the rotor 305 of the thread motor 301 is transmitted to the lead screw 311 through the transmission gear group 306 to rotate the lead screw 311, thereby driving the optical pickup (now shown).
As described above, the thread motor 301 is attached under the chassis 303 in a pendent state under the chassis 303 by means of the screw 304 and the like so that the outer peripheral portion of the stator substrate 302 is overlapped with the undersurface of the chassis 303, therefore, in the case that the screw 304 and the like are loosened due to vibration or shock, there is a fear that the thread motor 301 may fall from the undersurface of the chassis 303.
A playback device including a motor falling prevention portion 321 has been developing, which prevents further movement of the thread motor 301 when the thread motor 301 moves in a falling direction away from the chassis 303. The motor falling prevention portion 321 is formed in an approximately L-shape by a vertical piece portion 322 formed approximately vertically along an outer peripheral surface of the rotor 305 of the thread motor 301 at the undersurface side of the chassis 303 and a horizontal piece portion 323 formed by folding a tip portion of the vertical piece portion 322 at approximately right angles toward the center of the thread motor 301. A tip portion of the horizontal piece portion 323 overlaps the undersurface of the thread motor 301 slightly. When an amount of overlapping of the horizontal piece portion 323 is large, the falling prevention effect increases, however, the overlapping amount will be an obstacle when attaching the thread motor 301 to the chassis 303, therefore, the length of the horizontal piece portion 323 is determined in consideration of the circumstances. (For example, refer to JP-A-2005-322318 (Patent Document 1)).